Mercury vapor ballast and lamp assembly



Aug. 8, 1967 c. H. RONGEY ETAL 3,335,270

MERCURY VAPOR BALLAST AND LAMP ASSEMBLY Filed Sept. 2, l964 INVENTORS.

CL AREA/CE H. RCA/66X MHRSHALL 6. ZAVEQTN/K} HTTo ENE Y5 United States Patent 3,335,270 MERCURY VAPOR BALLAST AND LAMP ASSEMBLY Clarence H. Rongey, Granite City, 111., and Marshall G.

Zavertnik, Manchester, Mo., assignors to Killark Electric Manufacturing Company, St. Louis, Mo., a corporation of Missouri Filed Sept. 2, 1964, Ser. No. 394,029 Claims. (Cl. 24011.4)

The present invention relates to a mercury vapor ballast and lamp assembly, and particularly one that is explosion tight and weather-proof.

It is an object of the invention to provide a mercury vapor ballast and lamp assembly wherein the ballast can be a part of the total fixture, or, if desired, can be mounted separately from the lamp sub-assembly. It is a further object to provide such an arrangement which is both explosion tight and weatherproof. It is a further object to provide a ballast assembly of this type which contains the appropriate transformer and condenser equipment for ballast for mercury vapor lamps, that can be readily adapted to difierent types of ballast equipment, that can be completely opened up to render the ballast accessible for servicing, and that also "can be opened for wiring purposes, all without interfering with its explosion tight properties.

Another object of the invention is to provide a ballast sub-assembly that can be interposed in the connections by which a mercury vapor lamp may be mounted, making it possible to insert the ballast into the mercury vapor lamp sub-assembly and to permit the ballast to be removed and the mercury vapor lamp sub-assembly to be put together in its ordinary manner without the interposed ballast, all without any change in the structure of either the mercury vapor lamp sub-assembly or the ballast sub-assembly.

Other objects of the invention will appear from the description to follow. In general, the present invention includes a mercury vapor lamp assembly having an internally threaded cap or splicing box element, to which an externally threaded lamp housing may be secured in an explosion tight manner. The wiring for the lamp can be brought into the interior of the cap and there joined to wiring from a power supply. In the present invention there is a ballast sub-assembly that has an externallythreaded upper end designed to thread into the lamp cap in an explosion-tight manner by threads that are the same as those on the lamp housing. The ballast housing includes two components that, are hollow, preferably hemispherical and threaded together by an explosiontight threaded joint. The lower one of the two ballast housing members has lower internal threads of an explosion-tight nature that correspond to the internal threads on the previously-mentioned lamp housing cap, and these internal threads on the lower ballast housing member can receive the external threads previously mentioned that are provided on the main lamp housing element. Within the ballast housing are located a transformer and a condenser combination with appropriate wiring. In order to accommodate different types of ballast sub-assemblies, there is a plate that is designed to support different kinds of such sub-assemblies. Access openings are provided on the cap and on the ballast housing to permit the electrical wires to be spliced together or separated. Flame tight plugs seal the openings. The cap and ballast housings are preferably made of cast aluminum, and the ballast housing has external fins for dissipating heat.

In the drawings:

FIGURE 1 is an elevation of the mercury vapor lamp and ballast assembly;

FIGURE 2 is an enlarged diametrical cross-sectional view primarily through the ballast housing sub-assembly;

FIGURE 3 is a side edge view of a ballast supporting plate;

FIGURE 4 is a top view of the ballast supporting plate;

FIGURE 5 is an end edge view of the ballast supporting plate;

FIGURE 6 is a sectional view through the plate taken on the line 6-6 of FIGURE 4;

FIGURE 7 is a view looking upward into the upper ballast housing member showing the mounting lugs for the plate and the underside of the sealing receptacle for the wiring; and

FIGURE 8 is a view of the plate in an alternative position for a different kind of ballast.

As shown particularly in FIGURE 1, this assembly includes two principal sub-assemblies; namely, a mercury vapor lamp sub-assembly 10 and a ballast sub-assembly 11. Also illustrated is a cap or splicing box 12 that, as will be shown, can act as a cap for either the lamp subassembly 10, or the ballast sub-assembly 11. As shown, the cap 12 is hollow, having upper internal threads 15 that can be secured to a conduit 16 or other like sup port. It is desirable to have a set-screw 17, which can be supported in an upstanding flange 18, so that the cap and assembly can be secured in a particular angular orientation. The cap has a splicing cover 20 that is threaded into an access opening 21, the threads being of sufiicient length and size to provide an explosion tight, flame tight and weather-proof joint. As will appear, this access opening 21 provides access to the wiring to enable the wires to be joined or separated when the enclosing parts are assembled.

The cap 12 has internal threads 22 around its lower edge, of a size and length to provide an explosion tight connection. The ballast sub-assembly 11 is secured to the splice box or cap 12 by being attached to the threads 22. The ballast sub-assembly 11 includes a housing made up of an upper housing member 26 and a lower housing member 27, the two being separable as will appear.

The upper housing member 26 is here shown as being more or less hemispherical in shape. It has a wall thickness sufiicient to resist destruction from any predictable explosions within it. It has a plurality of fins 28 around its outside such as six, these preferably having the shape as indicated.

The upper end of the upper housing member 26 has an externally-threaded projection 30, its external threads interfitting with the threads 22 on the cap 12 to provide the explosion tight and flame tight joint previously mentioned. It is preferable that the internal threads be on the cap member 12 to minimize the possibility of having water get into the cap. A set-screw 31 can be provided to fix the member 27 in position when it is threaded into the cap 12.

The projection 30 on the upper ballast housing member 26 has a central cylindrical receptacle 32 of a length to provide for an explosion tight wiring seal. The receptacle 32 has an upper opening 33 and a lower opening 34, through which the wiring may pass. The two openings are preferably surrounded by inwardly projecting flanges. A pre-formed seal 38 of any insulating material, such as cardboard or plastic, is of a size to fit within the receptacle 32 and to be supported upon the bottom flange thereof. It receives the wires and holds them separated from each other. It also forms a bottom for any epoxy resin seal 40 that can be poured into the receptacle and permitted to harden in place. This rigid seal is of a proper length to provide an explosion tight seal around the wires and to isolate the interior of the cap 12 from the interior of the housing 11.

The interior of the upper housing member 26 has a plurality of integrally cast lugs 41. Four are shown here in FIGURES 2 and 7. These are adapted to hold selftapping screws designed to secure a ballast mounting plate 42 into the upper housing member 26, illustrated particularly in FIGURES 3-6 and 8. This plate 42 has four holes or notches 43 that are spaced to correspond to the locations of the holes in the lugs 41 formed integrally in the upper housing member 26. It can be seen that screws 44 (FIG. 2 and 8) can be introduced through the notches 43 and into the lugs 41 to secure the plate 42 in either its reverted or inverted position in the upper housing member 26.

The plate 42 at opposite ends has notches 46 that can receive the ends of a mounting strap as will appear. It also has two outwardly struck cars 47 provided with holes 48 (FIG. 6), one of which may be elongated for tolerance purposes. The plate 42 has two ears 49 turned out from a side edge, these having holes 50 (FIG. 6), one of which may also be elongated for purposes of tolerance.

In the arrangement illustrated in FIGURE 2, the plate is shown with the ears upstanding. An auto transformer 53 is secured to the under side of the plate 42 by a strap 54, the ends of which are locked into the notches 46 in a manner known in the art. An insulator 55 is placed above the strap 54 and the auto transformer 53 and a capacitor 56 is placed on the opposite side of the insulator. The insulator 55, the capacitor 56, and the auto transformer 53 are secured together by several layers of tape 57 that are wrapped around them in at least two places.

The lower open end of the upper housing 26 has internal threads 60 adapted to receive external threads on the upper end of the lower housing member 27. These threads are of size and length to provide an explosiontight joint between the two housing elements. Setscrews 61 can be used to secure the two housing members together and prevent their inadvertent separation or angular displacement. The lower housing member 27 is also made of metal of sulficient thickness to withstand predictable pressures within the housing, such as might be caused by an eruption of the ballast sub-assembly.

The lower housing member 27 has cooling fins '65 similar to the cooling fins 28 on the upper housing member 26. Between the six fins 65 are interposed somewhat smaller fins 66. The lower housing 27 is somewhat less truly hemispherical than is the upper housing, since its wall comes down more cylindrically for about half of its height and then curves inwardly on radii to a lower internally threaded opening 67. The fins 65 that correspond to the upper fins 28 extend substantially from the upper to the lower openings of this housing member 27.

The lower threaded opening 67 has threads corresponding to the internal threads 22 on the cap 12. Consequently the threads 67 are adapted to receive external threads on the upper end of the lamp wherein the ballast subassembly is interposed between the lamp 10 and the cap 12. A setscrew 68 can be used to hold these parts against being disconnected inadvertently. The threads 67 are also of sufiicient length and size to provide an explosion tight and fireproof joint.

The lower housing 27 also has an access opening 70 closed by a threaded cover or plug 71, the threads of which provide for an explosion tight and flame tight connection.

Some typical (but not limiting) dimensions include about 3 /2 inch diameter for the projection 30 at the top of the upper ballast housing; 2 to 8 /2 inches for the diameter of the ballast housing, inch for the height of the projection 30 above its shoulder, minimum wall thickness about 4 inch for cast aluminum, and threaded joints per standard specifications provided for explosion tight and flame tight joints.

Assembly and use FIGURE 1 illustrates the assembly of the lamp and ballast combination wherein the ballast 11 is interposed between the lamp 10 and the cap 12, this being possible because of the identity of the internal threads 22 on the cap and the internal threads 67 on the lower end of the ballast sub-assembly. With this arrangement, the ballast is an integral part of the fixture. It will be evident from a consideration of the total fixture made up of the lamp and ballast sub-assemblies, that a maximum of flexibility for assembly and servicing is provided. Thus an entire ballast sub-assembly may be removed and another one placed where necessary. Or, as will appear, the ballast housing can be opened up and the components of the ballast serviced or replaced as required. The mercury vapor lamp can be serviced in conventional manner. The individual components are isolated from each other by sealing means that can prevent explosions, transmission of flame or explosive gases from one to another. All of the external joints are flame tight and explosion tight as well as weather-proof.

FIGURE 2 illustrates a ballast sub-assembly that can provide high power factor. This is assembled as follows:

The mounting strap 54 is placed on the auto transformer 53, its ends being left free. The insulator 55 is placed against the auto transformer 53 and the strap 54, and the capacitor 56, is placed on the insulator, forming a sandwich. The capacitor insulator and auto transformer are bound together by the tape 57 (typically Temp-R- Tape TGV 1 in. width) using one or more complete turns of the tape 57 in at least two places, thus forming a complete unit of the auto transformer and the capacitor.

The foregoing unit is then mounted into the plate 42 and the ends of the strap 54 attached thereto, making a sub-assembly with the plate. This sub-assembly is fitted into the top housing member 26 and secured in place by self-tapping screws 44. These screws engage through the notches 43 in the plate and into previously-drilled holes in the lugs 41 cast into the housing member 26.

The several wires, here shown as four wires 80, 81, 82 and 83, are passed through the cylindrical sealing receptacle 32 usually before the auto transformer and capacitor sub-assembly are put into place. It is unnecessary here to consider the precise wiring arrangement, since different arrangements may be used in this type of equipment. Usually the ballast is provided with taps by which different wattages and power factor hook-ups can be employed. In any case the necessary wires are brought through the receptacle 32 from within the ballast housing, being first brought through the pre-formed seal 38 and, being maintained separate one-from-another, are then sealed with an epoxy seal 40 poured in above the seal 38. This seal is long enough to insure adequate flame and fireproofing between the interior of the cap 12 and the interior of the ballast housing.

When the lower ballast housing member 27 is threaded onto the upper one, and secured by the setscrew 61, the ballast unit is ready to be installed. It is threaded into the cap 12, its wires projecting thereinto. The plug 20 is removed from the cap 12, giving access to these wires and to the power lines, which thereupon can be spliced together as by the connectors -93 shown. Usually the wires are long enough to be pulled out through the hole 21, spliced and then pushed back, after which the sealing plug 20 is replaced and this connection is completed.

The lamp sub-assembly 10 has leads 96 and97 (two being shown) that emit through a sealing receptacle 100 that may be in all respects the same as the receptacle 32 and its sealing means. These wires 96 and 97 are extended into the ballast housing opening 67, and then the lamp sub-assembly is screwed into place in the ballast housing. The splicing or access plug 71 is removed, which gives access to the interior of the ballast housing. The wires 96 and 97 arethen spliced to the appropriate wires in the ballast housing by connectors 102 and 103. Then the plug 71 is replaced. The arrangement permits the lamp sub-assembly to be threaded in place with a flame tight and explosion tight joint without twisting the wires, as would be done if the wires had to be connected before the lamp sub-assembly were threaded into place.

Sometimes a different form of auto transformer is used. One such is illustrated in FIGURE 8. This auto transformer 110 has means for direct connection to the ears 47 and 49 as by screws 111. In this case the plate 42 is inverted from the position in FIGURE 2. The symmetrical arrangement of the notches 43 permits this to be done, using the same attaching lugs 41.

In some cases the ballast 11 is mounted apart from the lamp fixture sub-assembly, such as where a single ballast controls several lamps. In such case, the ballast box, having a cap or splicing box 12, is secured to a wiring conduit, in the manner shown at the top of FIGURE 2. To the other end of the ballast box can be fastened a fitting that can receive a conduit similar to the conduit 16, for conducting the wires to lamps at other locations. However, the illustrated form is the preferred one, since it enables the ballast to become an actual part .of the lamp sub-assembly. It will be noted that the ballast receptacle or box has fins on it which can dissipate the heat. This is a valuable feature. Preferably, the ballast box is made of cast aluminum, since this makes it light in weight and also dissipates the heat readily. The aluminum ballast box is corrosion resistant, non-sparking, and nonmagnetic, yet it can be made strong enough to withstand eruptions of the ballast which occur on rare occasions. The hemispherical shape of the housing parts also adds strength and increases the dissipation of heat.

When it is necessary to replace the auto transformer sub-assembly, it is not necessary to remove the entire ballast. The plug 71 is removed. The connectors 102 and 103 are taken off. The setscrews 61 are released and then the lower half 27 of the ballast box can be removed, giving access to the auto transformer sub-assembly. If it is necessary to replace that sub-assembly, the plug 20 is removed; the connectors 9093 taken apart; the setscrew 31 released; and the entire ballast housing removed. This last is necessary because if the auto transformer must be replaced, the seal 40 must be broken and a new seal in-' stalled. Connectors can be placed between the auto transformer leads and the seal 40, if desired, in which event the auto transformer sub-assembly can be replaced without disconnecting the wires within the cap 12 or replacing the seal 40.

Various changes and modifications may be made with- 'n the process of this invention defined by the claims appended hereto.

What is claimed is:

1. In a lamp assembly: a lamp and a ballast therefor, the lamp having a lamp housing and the ballast having a ballast housing; connecting means for releasably and directly joining the lamp housing and the ballast housing, including an external connector on one housing and a complementary internal connector on the other housing, the two connectors interfitting snugly over a distance suflicient to prevent flame transmission through the joint; a connector on another part of the ballast housing complementary to the first-named one on the ballast housing and the same as the first-named one on the lamp housing for association with another connector to form a second connecting means to secure the ballast housing to a conduit or the like; electric wire sealing means within the two connecting means to prevent transmission of flame from or into the ballast housing through either connecting means.

2. In a lamp assembly: a cap; a ballast housing; and a lamp housing; releasable connecting means between the cap and the ballast housing; the same kind of releasable connecting means between the ballast housing and the lamp housing; each connecting means including an external member on one part and a complementary internal member on the other part; the external and internal members fitting together snugly over a distance sufficient to prevent passage of flame through the joint; the ballast housing having one of the external and one of the internal members, and the cap and the lamp housing having one of the external and one of the internal members; the arrangement being such that the lamp housing can be connected directly to the cap, or to the ballast housing and the latter to the cap; a wire sealing receptacle in one connector member on the ballast housing and a similar wire sealing receptacle on the connector on the lamp housing, each sealing receptatcle being shaped to receive and constitute a through-passage for wires, and having space to receive a sealing compound around the wires to prevent passage of flame.

3. In the assembly of claim 2: the ballast housing comprising two hollow explosion resistant components, releasable flame tight connecting means joining them together, they being separate to give access to the interior of the housing, and ballast means secured to one of the components.

4. In electrical equipment: la ballast housing comprising two hollow components, releasable means connecting them together to form them into the housing, the releasable connecting means having parts interfitting snugly over a sufiicient area to inhibit flame transmission through the joint; each housing component having a connector ele- 5. In the equipment of claim 4: a ballast-holding plate in one housing component,

generally hemispherical and nector elements being generally at the polar positions.

7. In the equipment of claim 4: a ballast subassembly in the housing, including a plate removably secured to ballast housing, wires through the receptatcle, and fusible sealing around the Wires in the receptacle.

'8. In the equipment of claim 7: a splicing opening through a wall of the ballast housing, a removable clotight connection between the to aid in joining and releasing the said connecting means. 10. In the equipment of claim 9: the connecting means between the housing components comprising threads; one 2,041,189 5/1936 Keating et a1. 240-114 X of the housing components being nearer to heat than the 2,259,107 10/ 1941 Halvorson 24011.4 X other; the one having more fins than the other. 2,339,670 1/ 1944 Benson.

FOREIGN PATENTS References Cited t 5 1 5, 8. 6 1938 l UNITED STATES PATENTS 33 R f z 1,469,034 9/1923 Benjamin. RT N HE mmme" 1,907,295 5/1933 Hilli rd 240-114 X C. R. RHODES, C. C. LOGAN, Assistant Examiner. 

4. IN ELECTRICAL EQUIPMENT: A BALLAST HOUSING COMPRISING TWO HOLLOW COMPONENTS, RELEASABLE MEANS CONNECTING THEM TOGETHER TO FORM THEM INTO THE HOUSING, THE RELEASABLE CONNECTING MEANS HAVING PARTS INTERFITTING SNUGLY OVER A SUFFICIENT AREA TO INHIBIT FLAME TRANSMISSION THROUGH THE JOINT; EACH HOUSING COMPONENT HAVING A CONNECTOR ELEMENT FOR ATTACHMENT WITH ANOTHER ELECTRICAL DEVICE, THE CONNECTOR ELEMENTS BEING ONE AN EXTERNAL CONNECTOR AND THE OTHER AN INTERNAL CONNECTOR AND TWO BEING COMPLEMENTARY, WHEREBY THE HOUSING MAY BE INTERPOSED BETWEEN OTHERWISE DIRECTLY CONNECTABLE PARTS, AND MEANS ON AT LEAST ONE OF THE HOUSING COMPONENTS, TO SUPPORT AN ELECTRICAL BALLAST INSIDE THE HOUSING. 